Using allometry with fish size to estimate production to biomass (P/B) ratios of salmonid populations

Abstract

The ratio of annual production rate to average biomass (P/B) is sometimes used as a shortcut method of estimating production if biomass is known. P/B ratios vary among salmonid populations in different areas depending on the species, fish size and growing conditions. The hypothesis that annual P/B ratios for salmonid populations can be predicted from the allometric equation: P/B = a W-0.35 was investigated in this study. The allometric coefficient (-0.35) was obtained from the literature, and W was the average weight (g) of fish in the population. Plots of P/B versus fish weight for three species of salmonids, Salvelinus fontinalis, Salmo trutta and Salmo salar, showed a declining trend, with a slope consistent with the hypothesis. The coefficient a of the allometric equation was species and habitat dependent. The efficacy of using the allometric formula to estimate the P/B ratio of specific salmonid populations is examined.